This blog is sponsored by the Davistown Museum (www.davistownmuseum.org). The mission is to provide an overview of the accident at the Fukushima Daiichi reactor facilities; provide access to the most important websites for radiological surveillance data on the FD accident in Japan; promote our recently printed book Fukushima Daiichi: Nuclear Information Handbook; and provide updates about the situation in Japan, including reports on ongoing radiological monitoring and/or the lack thereof.

Thursday, August 11, 2011

The New York Times (August 9, 2011, pg. A8) has provided a second radiometric sketch of Fukushima Daiichi-derived fallout. The source of this map, which uses the standard reporting unit for ground contamination of Bq/square meter, is cited as the Nuclear Emergency Response Headquarters Office of Japan. The Times map caption notes “A Japanese computerized early warning system started to generate maps projecting the trajectory of radiation plumes from the Fukushima Daiichi plant within hours of the accident on March 11, but none of the maps were made available to the public until nearly two weeks later. The map below shows information made available to the prime minister’s office on March 16.” This clearly indicated Japan’s capacity to accurately monitor ground contamination on an hourly basis. The plume direction on March 16th matches the direction of maximum contamination noted in the Times on August 2nd, but contamination levels are significantly less at this early stage of the accident.

One of many flies in the ointment is the IRSN (France) sketch illustrating accident-derived air contamination dispersion on March 19th, reprinted on page 33 of the Davistown Museum’s Nuclear Information Handbook. The prevailing wind on this date resulted in significant but as yet undocumented ground contamination to narrow but extensive shoreline regions ~300 kilometers north of the accident site. This additional region of contamination highlights the need for public disclosure of a systematic survey of ground contamination throughout Japan – data the Japanese government is obviously still withholding.

All Japanese and concerned world citizens should also be reminded the cumulative ground deposition of Cs-137 from weapons testing-derived fallout is significantly less than 5,000 Bq/square meter in most nations. Given the map legend of soil contamination reprinted in the Aug. 2nd New York Times, which illustrates Fukushima Daiichi-derived fallout levels below 28,000 Bq/ square foot (300,000 Bq/square meter) in white without further analysis, Japan’s Nuclear Energy Response Headquarters has a moral as well as practical obligation to provide accident fallout-derived concentrations of radiocesium in a radiometric survey range of 300,000 Bq/square meter down to at least 5,000 Bq/square meter, the upper range of cumulative weapons testing fallout. This survey must be accompanied by full disclosure of the seven multiple interlocking meltdown event (MIME) hourly emissions since the accident began. A survey of washout pathway emissions, including gallons in/gallons out, gallons in storage, filtered gallons, curies recovered, and estimated releases of the Fukushima Daiichi accident is another component that needs further documentation.

On another related topic, Alex Roslin has written an informative review of radiation levels in Canada, as tabulated in March and April by Health Canada, which “detected massive amounts of radioactive material from Fukushima in Canadian air in March and April at monitoring stations across the country. The level of radioactive iodine spiked above the federal maximum allowed limit in the air at four of the five sites where Health Canada monitors levels of specific radioisotopes… The iodine-131 level in the air in Sidney peaked at 3.6 millibecquerels per cubic metre on March 20. That’s more than 300 times higher than the background level, which is 0.01 or fewer millibecquerels per cubic metre… One of the highest post-Fukushima radiation readings in North America came on March 27 in rainwater in Boise, Idaho. It contained 14.4 becquerels of iodine-131 per litre – 130 times the U. S. Environmental Protection Agency’s maximum level of 0.11 millibecquerels per litre… But nobody seemed to investigate how long the rainwater in Boise remained radioactive. Inexplicably, the EPA stopped monitoring Boise’s rainwater after the extremely high reading on March 27. The agency’s only other reading for the city was on March 22.”

Many thanks to Ken Belson, Norimitsu Onishi, and Martin Mackler of The New York Times and Alex Roslin of Straight.com for providing updates on the accident emissions from Fukushima Daiichi.

Tuesday, August 2, 2011

In an article on the attempt of a concerned citizen in Japan to make her own measurements of radioactivity contamination from the Fukushima Daiichi accident, The New York Times (August 1, 2011 pg. A1, A3) has provided the first isometric sketch of accident-derived radiocesium soil contamination that we have seen. The New York Times article republished a May 26, 2011 compilation of soil contamination levels of Cs-134 and Cs-137, in which it cites the US Department of Energy and the Japanese Ministry of Education, Culture, Sports, Science, and Technology as being the source of the data.

An anomalous characteristic of this article is the use of soil contamination reporting units expressed in becquerels per square foot instead of per square meter. One square meter contains 10.76 square feet. To compare the data in this article with the hundreds of reports of Chernobyl soil contamination, multiply the Bq/sq m by 10. Also consult the extensive Chernobyl fallout database republished in the Fukushima Daiichi: Nuclear Information Handbook.

The isometric sketch reprinted in this article shows an extensive area of contamination “279,000 or more Bq/sq ft” extending to the northwest of the accident site beyond the 18 mile radius (+/- 21 miles) towards the town of Iidate. This means that soil contamination in this area is approximately 3 million or more Bq/sq m. Maximum radiocesium contamination levels from the Chernobyl accident were +/- 5 million Bq/sq m, with contamination areas above 100,000 Bq/sq m occurring thousands of kilometers away from the accident site. The isometric map also shows contamination in the range of 93,000 to 279,000 Bq/sq ft extending +/- 26 miles to the northwest as well as approximately 6 miles to the southwest towards Shidamyo. These levels of soil contamination resulted from a brief shift in the prevailing trans-Pacific wind direction, which brought accident-derived emissions inland.

A startling aspect of this report is the use of white, rather than grays, to signify areas with contamination “less than 28,000 Bq/sq ft”. The use of the color white implies the areas outside of the gray were un-impacted, when, in fact, large areas away from the accident site have soil contamination, which may approach 300,000 Bq/sq m. During the 1960s, cumulative weapons-testing-derived radiocesium contamination peaked at less than 5,000 Bq/sq m, yet there was worldwide concern about the health physics impact of fallout in this range of soil contamination. This isometric map inadvertently graphically illustrates the need for a much more comprehensive survey of soil contamination levels throughout Japan. The Fukushima Daiichi accident scenario is complicated by the fact that undocumented emissions are still occurring from all seven accident sites. Changes in prevailing wind directions due to the advent of the rainy season also raise the possibility of additional contamination occurring throughout Japan from both ongoing emissions and re-suspended contamination.

The article in The New York Times provides the first hint that detailed soil contamination data is available and can be easily converted into isometric maps that the general public can understand. The use of 300,000 Bq/sq m (28,000 Bq/sq ft) cutoff for reporting radiocesium soil contamination is absolutely unacceptable. As a matter of both honor and practicality, a much more detailed post-rainy season survey of accident-derived contamination should be the demand of all Japanese citizens. The extensive documentation of the many radioisotopes released by the Chernobyl accident, numerous useful definitions, and a survey of protection action guidelines is easily accessible for any concerned citizen interested in the impact and evaluation of nuclear accidents in Fukushima Daiichi: Nuclear Information Handbook. This Handbook, sponsored by the Davistown Museum may be purchased through Amazon.com or ordered from the Davistown Museum.

The New York Times article focuses on the attempts of Japanese private citizen Kiyoko Okoshi to monitor radiation in the area of her home in Iwaki Town in response to the lack of accurate data from the Japanese government. This article may serve the useful purpose of alerting all concerned citizens to the failure of the Japanese government and TEPCO to execute comprehensive monitoring of accident emissions in the form of a survey of soil contamination levels by the indicator nuclides Cs-137 and Cs-134. The lack of this easily compiled data also emphasizes the lack of public disclosure of real time monitoring of ongoing accident emissions, which continue to occur in both the water washout pathway and as volatile airborne emissions.

University of California, Berkeley Nuclear Engineering Dept.; http://www.nuc.berkeley.edu/UCBAirSampling -- has data on radiation sampling in milk, rainfall, river water, and air in becquerels and equivalent dose